Bulletin #13

Revised August 22, 2006

Waterproofing Membrane And Bedding Systems Over Which Ceramic And Clay Products Can Be Installed

Definitions of Materials

Waterproof membranes are available for use under both thin-bed and thickbed installations. A ceramic tile installation does not necessarily constitute a waterproof barrier against water penetration. If the installation is required to be waterproof, the waterproofing must be planned. This could be under the jurisdiction of the Tile Contractor. (Ceramic Tile Contractors are encouraged to incorporate this work in their bids when specified).

Modifications to existing technology,as well as new technology, have made available to the tile industry products such as emulsions, solution materials, liquid elastomers, asphaltic compounds and sheet stock for a great number of chemical-resistant and waterproof tile-setting applications. Most of these are cold-applied, room temperature-curing systems-, possessing good abrasion resistance and flexibility over a broad thermal range.

Unique to certain of these systems is their ability to be used as an integral membrane and thin-bed setting system for various tile and ceramic units over concrete, steel and wood substrates. Some of these systems also have high compressive strength and excellent load bearing capabilities. These membranes may be used as traffic surfaces in residential, light and moderate performance level areas. There are several different types of waterproof membrane systems currently being marketed.

These systems are either a one, two or three component material applied in liquid/paste form at a thickness of 20 to 125 mils (.020½-.125½). These materials cure into a continuous membrane, some with load bearing capabilities. Some of these materials have integral reinforcing fabrics for tensile strength and minor crack bridging properties. Based on a survey of common, currently marketed materials, these systems are compatible with many contemporary tile setting materials and grouts.

Another type of material which does the same as the above, is designed to be used as a combination waterproofing and setting bed in one application.There is similarity in function to materials described above, but care should be taken not to use the type designed solely as waterproofing as a combination waterproofing and setting bed. Adhesion, flexibility, crack bridging ability on concrete, primed steel, wood, plastic and Cementitious Backer Units are excellent. In addition to the above chemical compounds, waterproofing membranes are also available in flexible sheet goods form. Materials are available for both vertical and horizontal applications. A major consideration must be that the material used to provide the waterproofing is compatible with the material used to set and grout the tile products. In all probability, a guarantee may be required by the architect, both as to the waterproofing and tile installation.

Liquid or Semi-Mastic Membrane
When the surface has been properly prepared to satisfy the specifications and requirements of the manufacturer of the waterproofing membrane, the material is then applied by trowel, or a "pour and level" method, until a desired thickness is achieved. Depending upon the product, this may require one, two or three applications. Depending upon the manufacturer’s recommendation, a certain time period and/or a physical appearance check method must be allotted to allow the membrane to cure or catalyze before the tile installation can begin.

Depending upon the type of waterproofing product used, the manufacturer may require the tile products be set using a troweled application of the same product, or may suggest installation with normal thin-bed setting systems. It is imperative that the installer of the waterproofing membrane be certain of the compatibility between that product and the product used in the setting system. The manufacturer of both the waterproofing membrane and the tile setting material must determine and be certain of a satisfactory installation. Without this assurance, it is not possible to warrant a satisfactory installation. Consider the maximum required performance level outlined in the TCA Handbook (ASTM C-627). A rigid layer of ceramic tile and grout bonded to a resilient membrane may be satisfactory only for residential and light performance levels. Moderate, heavy and extra heavy installations should be reviewed with the specific membranesystem manufacturer.

Flexible Sheet Goods

If this method of waterproofing is used, all details of the manufacturer’s installation system must be carefully followed. The installation system must include waterproofing of the slab area as well as the installation of the tile products.

Anti-Fracture Membranes

Some proven products on the market today are designed to eliminate surface cracking due to sub-surface failures. They are not necessarily designed to waterproof the installation.


Regardless of the waterproofing system used, manufacturer’s instructions must be followed regarding the length of necessary "cure" timebefore grouting begins. Grouting should be done with a specified product in accord with existing industry practices. Normal clean-up methods would follow.